There is a growing demand for methods which allow the recycling of particles such as dust, larger particles and pieces, that contain extractable metal values, to processes for recovering such metal values. The dust and particles under consideration often include by-products and waste products of various metallurgical refining, gas cleaning, metal working and various other metallurgy-related operations. A particularly metal rich by-product of metallurgical operations contains sulphates of value metals. The metal sulphates are often very fine and can be easily blown away by the updraft in the converter or similar metallurgical extractive installation when attempts are made to feed or charge them to such installations. Thus there is a need for an inexpensive method for forming shape-retaining agglomerates of value metal sulphate containing particles.
Metal sulphate containing fine particles are in some instances to be stored, transported or are to be used as backfill. The fine particles can easily be blown away by wind or draft and thus need to be agglomerated and anchored for environmental reasons.
It is to be noted that calcium sulphate is one of the products of several known processes for capturing and absorbing sulphurous oxides contained in exhaust and flue gases in metallurgical processes. Such absorption is usually conducted by limestone, calcium and magnesium oxides and hydroxides, and carbonates, and similar alkali and alkaline earth metal containing absorbents. The by-and waste products of such processes are usually predominantly calcium sulphate, other metal sulphates are only present as impurities. In other words, conventional sulphurous gas absorbing processes yielding calcium sulphate and/or gypsum which may be agglomerated in a subsequent step, are not considered to be relevant to the products to be treated in the present process, nor to the discussion with respect to the operation and implementation of the present invention.